1. Field of the Invention
The present invention relates to a method and an apparatus for drying ceramic articles molded by extrusion.
2. Description of the Related Art
In fabricating ceramic molded articles, a clay-like ceramic material is extruded, dried and baked.
A conventional apparatus for drying ceramic molded articles is disclosed, for example, in JPP (Japanese Unexamined Patent Publication) 2000-44326, in which a part of the path for conveying extruded ceramic molded articles is covered by a drying chamber, and the ceramic molded articles being conveyed through the drying chamber are dried by being irradiated with microwave energy.
In this conventional drying apparatus, the microwave energy is required to be slowly and uniformly radiated in order to dry the ceramic molded articles uniformly without any strain. For this purpose, it is common practice to carry out the drying process in which a plurality of ceramic molded articles are continuously charged and conveyed in a drying bath longitudinally along the direction of conveyance to radiate microwave energy, with low energy density, over a long time.
This conventional drying apparatus poses the problem described below. Specifically, in the case where the ceramic molded articles are arranged at irregular intervals in the drying chamber of the drying apparatus, the amount of microwave energy absorbed into the ceramic molded articles lacks uniformity.
Especially in the case where the train of ceramic molded articles in the drying chamber is temporarily disconnected, the neighboring ceramic molded articles may be overdried by absorbing an increased amount of microwave energy. In the conventional drying apparatus, therefore, the ceramic molded articles are required to be charged into the drying bath continuously without any intervals.
This is especially true in the case of a ceramic molded article having a honeycombed structure in which cell walls, arranged in a honeycomb pattern to partition cells, are easily strained by being dried unevenly.
In the case where the extrusion molding process cannot be carried out continuously, therefore, the clay-like ceramic material produced by extrusion must be stored temporarily to secure a predetermined quantity of the clay-like ceramic material in the drying apparatus, in order to continuously charge them into the drying apparatus.